Quick recap
The war against the Titans comes to a head. Percy tries to blow up Luke's ship, but a spy at camp ruins the plan, and Beckendorf dies. Poseidon sends him back to camp, where he hears the prophecy about his sixteenth birthday. With Nico, Percy goes down to the Underworld and bathes in the River Styx, which makes him nearly invulnerable. When New York falls asleep under a spell, the campers, the Hunters, the centaurs and other allies defend Olympus while the gods are busy with Typhon. In the throne room, Percy and Luke meet one last time, and the choice the prophecy foretold is made.
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